In a “classic” question that is re-appearing again on the main page (see here), Cecil seems to give a great explanation to something that was not even asked.
The inquirer wanted to know why a chopper doesn’t spin around due to the main rotor’s spinning (a reasonable question based on Newton’s 3rd law). The simple answer is because of the tail rotor – it creates a torque on the vehicle in the opposite direction, thus resulting in a stable, forward-facing helicopter.
The answer given by Cecil launches into some theory about how a helicopter gains forward thrust from the pitch of the rotors, etc. But am I the only one who thinks that this answer was quite a bit off the mark?
Read the question again. The person says that he knows that the helicopter does not spin like a top due to action of the tail rotor. What Cecil says about the pitch of the blades is spot-on. I am a retired Navy Helo mechanic, I have worked on Helos for about 12 years now.
Um, no. The questioner wanted to know how helicopters move forward and backward:
In fact, in his question, I-from-Chicago says he knows the purpose of the tail rotor:
Unca Cecil answered exactly what the questioner asked.
ETA: Dammit! Ninja’d by the Navy!
Hint: The tail rotor is called the ‘anti-torque rotor’.
Helicopters are fascinating. (Also fun.) How does the anti-torque rotor counteract torque? With thrust. In American helicopters the rotor turns left, so the fuselage tries to yaw right. Left pedal is used to counteract that, so that little fan is blowing to the left. The result is ‘translating tendency’, which is the tendency for the helicopter in hover to move sideways; in American helicopters, to the right. This is compensated for in one of two ways: The transmission is mounted at a slight angle so that the main rotor disc is tilted to the left (in American helicopters), or the flight controls are rigged to give the rotor disc the required sideways tilt when the cyclic is centered.
Gotcha. Upon rereading it, yes the questioner clearly stated that he understands the tail rotor. My bad.
I now see that my issue was with the headline, which asks, “How do helicopters keep from spinning around uncontrollably?”
Doesn’t THAT sound like a question about the anti-torque rotor? Shrug.
Everything I read about helicopters makes me never want to ride in one. Harder to fly than airplanes, and if anything goes wrong, whether due to pilot error or mechanical trouble, it falls like a rock rather than gliding.
Is Helo really the abbreviation for helicopter, like Convo (conversation) and Sando (Sandwich)?
That’s actually not true; helicopters can do what’s called “autorotation”, which means that the transmission automatically disengages the rotor from the engine, and lets it freewheel, and the pilot lowers the collective pitch. Since a helicopter is literally a rotary-wing craft, as long as it has air coming up through the rotor, it’ll continue to spin, and continue to provide lift, and essentially does the helicopter equivalent of gliding.
Most helicopters rotors can in theory auto-rotate to a safe landing, assuming the rotor is still operable and under control. It’s not a guarantee, but when you look at the large commercial planes they can rarely land safely when there is serious mechanical trouble. Helicopters aren’t as safe overall as airplanes and depending on which figures you look at the difference isn’t necessarily as great. Statistics on helicopters may be skewed because they are used in ways planes wouldn’t be by traveling close to structures and for emergency operations. I’ve seen a claim that some small helicopters have much better safety records than fixed wing planes in general.
(I just finished reading “Chickenhawk” for the umpteenth time, so this is a very timely topic for me.)
I understand the autorotation bit, but the weak link to me seems to be that tail rotor. If anything at all happens to the linkage, it seems like the aircraft will just spin wildly, making it difficult if not impossible for the pilot to autorotate to any chosen place.
Is it the case that a tail rotor problem == almost certain disaster? If not, how does the pilot address the problem?
Been working with helicopters (albeit from a desk chair) for years and have ridden in more than a few, and they are, like any mechanical craft, as safe as their maintenance…well-maintained means less chance of trouble.
Others have mentioned auto-rotation so I won’t, except that it is something all helicopter pilots have (or should) learn.
But there is no sensation (or view) quite like riding in a helicopter.
Oh, and remember the basic rule: Helicopters DO NOT FLY: They beat the air into submission. 
I don’t have the link but I saw a blurb yesterday saying Airbus and Uber were linking up for on demand helicopter transportation. Should prove interesting if they do it.
In case of tail rotor failure, autorotate. No torque, no need for an anti-torque rotor. You can extend the glide by applying power carefully.